The jury in the murder trial of legendary music producer Phil Spector has found it impossible to reach a unanimous verdict.

But why was it so difficult to reach a decision?

Actress Lana Clarkson was found dead from a gunshot wound to the mouth in Phil Spector's home in California in February 2003.

With no witnesses to the shooting except Mr Spector himself, who chose not to take to the stand, it was always going to be a difficult case. Prosecutors claimed he pulled the trigger, while defence lawyers said she shot herself.

In the end, some jurors decided the evidence was not sufficiently convincing.

THE CRIME SCENE

What happened in the two hours after Mr Spector and Ms Clarkson returned from a nightclub was the subject of heated claim and conjecture in court.

Jurors saw a photo of Ms Clarkson's legs, showing where the gun fell

Candles were lit on the fireplace and an empty bottle of tequila and two glasses with the pair's fingerprints were found on the coffee table in the living room.

The jury was told Mr Spector's DNA was found on one of Ms Clarkson's breasts, but there was no sign of intercourse or assault.

In the foyer was a leather briefcase containing some over-the-counter medication and a packet holding one Viagra pill with empty spaces for two more.

There was also a bureau with a draw that was partially opened. In it was a holster that matched the snub-nosed Colt Cobra revolver that killed Ms Clarkson.

She was found sitting in a chair with her legs outstretched and a leopard-print handbag over her shoulder.

She had an "intra-oral" gunshot wound, according to the criminal terminology.

THE CHAUFFEUR

Mr Spector's Brazilian chauffeur Adriano De Souza, who called the emergency services on the night of the death, was a key witness.

Chauffeur Adriano De Souza claimed Mr Spector confessed

Mr De Souza was outside the producer's property when he said he heard a "pow" at about 5am.

His boss emerged from the house several minutes later and told him: "I think I killed somebody," the driver testified.

De Souza then asked: "What happened, sir?" The producer shrugged.

The driver told the 911 operator: "I think my boss killed somebody."

When the operator asked why, De Souza stammered: "Because, he, he have a lady on the, the floor and he have a gun, in, in his hand."

But the defence team questioned De Souza's version of events.

The jury was told that less than 24 hours after the shooting, De Souza was asked by police if he could recall Mr Spector's exact words. "I think so. I think, I'm not sure. It's my English," he said.

FORENSIC EVIDENCE

At the trial, one of the crucial questions was whether the forensic evidence proved Mr Spector was close enough to the victim to have been able to shoot her in the mouth.

Phil Spector's gun was shown in court

Mr Spector's lawyer Linda Kenney-Baden told jurors the absence of gunshot residue and blood from his sleeves showed he could not have shot Ms Clarkson.

"Those sleeves by themselves prove Phillip is innocent," she said.

Moreover, more forensic experts said Mr Spector's DNA and fingerprints were not found on the gun.